MXPA00002576A - Interference pigments - Google Patents

Abstract

The present invention relates to the interference pigments based on platelet-shaped substrates coated with several plates and comprises at least one layer of the sequence comprising: (A) a coating having a refractive index of n > 2.0, (B) a colorless coating having a refractive index of n < 1.8, and (C) a non-absorbent coating of refractive index and, if desired, (D) an outer protective layer

Description

Interference Measures The present invention relates to interference pigments based on platelet-shaped substrates with multilayer coating.

The glossy pigments or pigments of special effects are used in various fields of industry, especially in the automotive finishing sector, in decorative coatings, in plastics, paints, in printing inks and in cosmetic formulas.

The lustrous pigments that exhibit a color change dependent on the angle between two or more interference colors have a set of color that makes them of particular interest for automotive finishes and are in connection with value documents protected against filing. Pigments of this type are known on the basis of platelet-shaped substrates with multilayer coating.

REF .: 32933 Generally, the interference pigments consist of platelet-shaped substrates with a thickness from 200 to 1000 nm which are coated with metal oxides or mixtures of highly refractive metal oxides with a thickness from 50 to 300 nm . The optical properties of these pigments are determined in a critical manner by the refractive index of the metal oxide layer. In addition to the possibility of using techniques of chemical vapor deposition (CVD), or techniques of physical deposition to steam (PVD) to prepare the layers of metal oxide that have high densities and therefore refractive indexes that are near the optimum , the deposition of metal oxides in. substrates in the form of finely divided platelets are frequently carried out to the title holder aqueous solutions, normally acid solutions of metal salts against a solution of sodium hydroxide in the presence of a substrate, as described, for example, in DE 14 67 468 and DE 20 09 566.

A disadvantage of the vapor deposition technique is the high costs involved. For example, US 4,434,010 describes a multilayer interference pigment consisting of a core layer of a refractive metal, such as aluminum, and alternating layers of two transparent and electrical materials with a high refractive index respectively, such as titanium dioxide and silicon dioxide, for example. This multilayer pigment is preferably used for values protected against counterfeiting.

JP H7-759 discloses a multilayer interference pigment with a metallic luster, for which a substrate is coated with alternating layers of titanium dioxide and silicon dioxide. The substrate comprises flakes of aluminum, gold or silver, or mica or glass, with a metal coating. However, the depth effect which is desired and characteristic for the interference pigments can not be generated. This is due to the total reflection of the light on the metal layer which forms the center. Consequently, the interference effect is limited to the layers that are located in the metal layer. In addition, the lack of transparency greatly restricts the various possibilities for a combination with more pigments in the formulas related to the application.

US 3,438,796 and US 5,135,812 describe, for example, glossy metal pigments having an opaque aluminum center film coated on both sides in alternation with dielectric films of a low refractive index, such as silicon dioxide magnesium fluoride and with partially transparent metal films, such as for example chromium or aluminum films,. Due to the preparation process, the central metal film of these pigments is coated only on the upper and lower sides of the platelets, while the lateral areas constitute interrupted edges and remain open towards the middle.

DE 44 05 494, DE 44 37 753, DE 195 16 181 and DE 195 15 988 describe glossy pigments prepared by coating metal platelets, especially aluminum flakes, with metal oxide layers with a low refractive index, such as with a layer of silicon dioxide and with non-selective absorption metal oxide layers or metal layers of a high refractive index, using CVD or chemical techniques in water.

Frequently, glossy pigments based on metal substrates have good performing properties that include good opacity, but the result of the application, for example, such as in paint, is a "strong" metallic luster, which is frequently undesirable.

The lustrous pigments based on transparent pigments in the form of platelets which do not have this "strong" metallic glaze are the subject of WO 93/12182. The mica flakes are covered with a layer of metal oxide of a high refractive index such as Ti02, and with a non-selective absorption layer. Depending on the thickness of the IO2 layer, when viewed at a right angle these pigments exhibit a particular color interference which becomes increasingly weak as the angle of observation becomes more oblique, to which they eventually turn gray or black The interference color does not change, but a decrease in color saturation is observed.

JP 1992/93206 claims that glossy pigments based on glass flakes or mica particles that are coated with a layer of opaque metal and with alternating layers of SIO2 and Ti02.

EP 0 753 545 discloses lustrous pigments based on substrates in platelet fcona and non-metallic with multilayer coatings, which have a high refractive index, and which are at least partially transparent to visible light and have at least one layer assembly comprising a colorless coating with a low refractive index and a refractive coating which absorbs selectively or non-selectively. The disadvantages of this invention are costly and technically complex preparation processes, and the frequent difficulties of reproducing the pigments with the quality of the desired product.

The aim of the present invention is to provide a particularly transparent interference pigment having strong interference colors and / or a strong angular dependence on interference colors which is notable for its advantageous performance properties and which can at the same time be prepared in simple form.

Surprisingly, an interference pigment has now been found which is based on substrates in the form of platelets with multilayer coating and comprising a particular arrangement of optically functional layers by which particular optical effects are achieved.

Therefore, the invention provides interference pigments based on substrates in the form of platelets are multilayer coating comprising at least one sequence of layers comprising: (A) a coating having a refractive index of n > 2.0, (B) a colorless coating having a refractive index of n < 1.8, and (C) a non-absorbent coating with a high refractive index and, if desired, (D) an outer protective layer.

The invention also stipulates the use of pigments of the invention in paints, lacquers, printing inks, ceramic materials, glasses and cosmetic formulas.

Suitable base substrates for pigments with several cells of the invention are first opaque and second transparent substances in the form of platelets. Preferred substrates are phyllosilicates and materials in the form of platelets and with metal oxide coating. Of particular convenience are natural and synthetic micas, talc, kaolin, platelet-shaped iron oxides, bismuth chloride, glass flakes, SIO2, AI2O3 or IO2, synthetic ceramic flakes, carrier-free synthetic platelets, LCP and others. comparable materials.

The size of the base substrates per se is not critical and can be matched to the application of the particular objective. In general, platelet-shaped substrates have a thickness between 0.1 and 5 μm, and in particular between 0.2 and 4.5 μm. The extension in the other two dimensions is usually between 1 and 250 μm and preferably between 2 and 200 μm and, in particular, between 5 and 50 μm.

The thickness of the individual layers of high and low refractive index of the base substrate is essential for the optical properties of the pigment. For a pigment with deep interference colors, the thickness of the individual layers must be precisely adjusted with respect to one another.

If n is the refractive index of a thin layer and d is its thickness, the interference color of this layer is defined by the product of n • d (n • d = optical thickness). The colors that result from such a film under a perpendicular incidence of light in reflected light results in an intensification of the wavelength of light 4? = »N» d 2N-I and by attenuating the wavelength of light ? • n * d N where N is a positive integer The variation in color that results from the increase in the thickness of the film is a consequence of the intensification or attenuation of certain wavelengths of light through interference. If two or more layers in a multilayer pigment have the same optical thickness, the color of the reflected light becomes more intense while the number of layers increases. In addition to this, it is possible to achieve through a suitable selection of the thickness of the layers, a particularly strong variation of the color as a function of the angle of observation. The so-called sharp fall of color develops. The thickness of the individual layers of metal oxide, regardless of their refractive index depends on the field of application and is generally 10 to 1000 nm, preferably 15 to 800 nm and, in particular, 20-600 nm.

The lustrous pigments of the invention feature a coating (A) with a high refractive index • in combination with a colorless coating (B) of a low refractive index and which is located on it in a high-index non-absorbent coating of refraction. The pigments may comprise two or more identical or different combinations of layer assemblies, although it is preferred to coat the substrate with only one set of layers (A) + (B) - + • (C). In order to make the color drop more intense, the pigment of the invention can comprise up to four layer assemblies, although the thickness of all the layers in the substrate must not exceed 3μm.

The layer (A) of high refractive index has a refractive index of n > 2.0, preferably from n > 2.1. The materials suitable as the material for layer (A) are all materials known to the right-handed worker which have a high refractive index, are film-like and can be applied permanently to the particles of the substrate. Particularly suitable materials are metal oxides or metal oxide mixtures such as Ti02, Fe2? 3, Zr02, ZnO or Sn? 2, or compounds with a high refractive index such as, for example, iron titanate, hydrate iron oxide, titanium suboxides, chromium oxide, bismuth vanadate, cobalt aluminate, and also mixtures or mixed phases of these compounds with each other or with other metal oxides.

The thickness of the layer (A) is 10-550 nm, preferably 15-400 nm and in particular, 20-350 nm.

The colorless materials of low refractive index for the coating (B) are preferably metal oxides or the corresponding oxide hydrates, such as SIO2, AI2O3, 2-Q10 (0H), B2O3, or a mixture of these metal oxides . The thickness of layer (B) is 10-1000 nm, preferably 20-800 nm and particularly, 30-600 nm.

Particularly suitable materials for the non-absorbent coating (C) of a high refractive index are colorless metal oxides such as TiO 2, Zr 2, Sn 2, ZnO and BiOCl, and mixtures thereof. The thickness of the layer (C). it is 10-550 nm, preferably 15-400 nm, and in particular 20-350 nm.

In addition to the normal assembly of the layer (A) + (B) + (C), which may be present up to 4 times in the pigment of the invention, there are other preferred embodiments. For example, between the substrate (S) and the layer (B), between the layer (A) and (B), between the layer (B) and (C) and / or between the layer (C) and the upper layer (D), the pigment of the invention may have an additional absorbent or non-absorbent layer [(Si), (Al), (Bl), (Cl) ] The thickness of the intermediate layers is 1-50 nm, preferably 1-40 nm and in particular 1-30 nm.

A particularly preferred embodiment is the coating of the substrate with the following layer assembly: (SI) optional, Sn02 (A) Ti02 or Fe203 (B) Si? 2 (B) optional, Sn? 2 (C) Ti02 (C) final coating related application Coating substrates with layers (A) and (C) of high refractive index, a layer (B) of low refractive index and if desired, more colorless or colored coatings produce pigments whose color, brightness, opacity and Angular dependence on the perceived color can vary within very wide limits.

The pigments of the invention are easy to reproduce by virtue of the generation of two or more interference layers of high and low refractive index, the precisely defined thickness and the smooth surface of the finely divided substrates in the form of a platelet.

The metal oxide layers are preferably applied by chemical methods in water, it being possible to use the techniques of coating chemicals in water developed for the production of lustrous perliscent pigments. Techniques of this type are described, for example, in DE 14 67 468, DE 19 59 988, DE 20 09 566, DE 22 14 545, DE 22 15 191, DE 22 44 298, DE 23 13 331, DE 25 22 572, DE 31 37 808, DE 31 37 809, DE 31 51 343, DE 31 51 354, DE 31 51 355, DE 32 11 602, DE 32 35 017 or otherwise in other documents d < _ patents and other publications.

In the case of a fresh coating, the particles of the substrate are suspended in water, and one or more hydrolysable metal salts are added at a pH that is suitable for hydrolysis and are chosen in such a way that the metal oxides or hydrates of the metal oxides precipitate directly on the platelets without any possibility of secondary precipitation. Usually the pH is kept constant by a simultaneous metered addition of a base and / or an acid. Subsequently, the pigments are separated, washed and dried and, if desired, calcined, it being possible to optimize the calcination temperature with respect to the present coating in particular. In general, the. Calcination temperatures are between 250 and 1000 ° C, preferably between 350 and 900 ° C. If desired, after the application of the individual coatings the pigments can be separated, dried, and if desired, calcined before being resuspended for application by precipitation of more layers. The coating can also be carried out in a fluidized bed reactor by means of a phase gas coating, in which case it is possible, for example, to make appropriate use of the techniques proposed in EP 0 045 851 and EP 0 106 235 for prepare the pearlescent glossy pigments.

The metal oxide with high refractive index used is preferably titanium dioxide and / or iron oxide, and the metal oxide of low refractive index preferably used is silicon dioxide.

For the application of the titanium dioxide layers, preference is given to the technique described in US Pat. 3, 553, 001.

Slowly add to a suspension of the material to be coated, an aqueous solution of titanium salt, heat to 50-100 ° C, and with a pH of about 0.5-5, it is kept substantially constant by simultaneous dosing. of a base, for example, of an aqueous solution of ammonium or an alkali metal hydroxide solution. As soon as the desired thickness of the Ti0 precipitate layer is reached, the addition of both the titanium salt solution and the base is completed.

This technique, also referred to as the titration process, is notable for the fact that it prevents an excess of titanium salt. This is achieved by supplying to the hydrolysis process only the amount per unit of time that is necessary for a uniform coating with the hydrated io2 and that can receive per unit time the available surface area of the particles to be coated. Therefore, there is no on the surface to be coated, production of hydrated titanium hydroxide particles without precipitating.

The application of the silicon dioxide layers can be carried out, for example, as follows. A solution of sodium or potassium silicate in a suspension is dosed, heated to approximately 50-100 ° C, the substrate to be coated. The pH is kept constant at about 6-9 by the simultaneous addition of a dilute mineral acid such as HCl, HN03 or H2SO4. As soon as the thickness of the desired layer of SIO2 has been reached, the addition of the silicate solution is completed. Subsequently, the batch is removed for approximately 0.5 h.

In order to intensify light stability and wear stability, it is advisable to subject the finished pigment to a subsequent coating or subsequent treatment process, depending on the field of use. Such suitable processes are those described, for example, in DE-C 22 15 191, DE-A 31 51 354, DE-A 32 35 017 or DE-A 33 34 598. Such a subsequent coating further increases the chemical stability or facilitates the handling of the pigment, especially its incorporation in different media.

The pigments of the invention are compatible with a large number of color systems, preferably with the sector of lacquers, paints and printing inks, especially of security printing inks. Due to the non-reproducible optical effects, the pigments of the invention can be used in particular to produce valuable documents with protection against forgery, such as bank notes, checks, check cards, credit cards, ID cards, etc. In addition, the pigments are also suitable for laser marking of paper and plastics and for applications in the agricultural sector, such as, for example, greenhouse glass films.

Therefore, the invention also provides for the use of pigments for formulas such as in paints, printing inks, lacquers, plastics, ceramics and glass and materials. for cosmetic preparations.

It is then the case that for the various purposes, the applications of multilayer pigments can also be advantageously used in combination with other pigments, the examples being transparent white and fading white, black and colored pigments, and with oxides of iron in the form of platelets, organic pigments, holographic pigments, LCP (liquid crystal polymers) and conventional transparent pigments, of black and colored luster, based on platelets coated with metal oxide, mica and SiO2, etc. The multilayer pigments can be mixed in any proportion with traditionally commercial pigments and diluents.

It is intended that the examples that follow are to illustrate the invention, but without placing any limitation on it.

Examples Example i Heat at 80 ° C, 100 g of mica (PSD 10-60 μm) in 2 1 of deionized water. At this temperature, 430 g of an iron (III) chloride solution (14.25% Fe) are metered in by vigorous stirring. During this addition, the pH is kept constant at 4.0 using an aqueous solution of sodium hydroxide (32% NaOH). Subsequently, the pH is lowered to 1.8 using hydrochloric acid (15% HCl) and at this pH 30 ml of a TÍCI4 solution (400 g of TiCl / l) are added. During this In addition, the pH is maintained coily using an aqueous solution of sodium hydroxide (32% NaOH). Subsequently, the pH is raised to 7.5 using an aqueous solution of sodium hydroxide (32% NaOH) and at this pH a solution of 252 g of sodium silicate (27% of SIO2) is added in 252 g of deionized water. During this addition, the pH is kept constant using hydrochloric acid (15% HCl).

Subsequently, the pH is lowered to 2.0 using hydrochloric acid (15% HCl) and at this pH, a solution of 3 g of SnCl x 5 H2O and 1 ml of hydrochloric acid (37% HCl) is added in 90 ml. of deionized water. During this addition the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). The pH is subsequently lowered to 1.8 using hydrochloric acid (15% HCl) and at this pH 655 ml of a TiCl solution (400 g / 1) are dosed. During this addition the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). After the addition of the TLC14 solution, the mixture is stirred for 15 min and the product is filtered, washed with deionized water and dried at about 10 ° C, then calcined at 850 ° C for 45 minutes. The interference pigment obtained has an intense reddish violet interference color.

Example 2 100 g of mica (PSD 10-60 μm) in 2 l of deionized water are heated at 80 ° C. At this temperature, 43Og of a solution of iron (III) chloride (14.25% Fe) is metered in with vigorous stirring. During the course of this addition, the pH is kept constant er, 4.0 using an aqueous solution of sodium hydroxide (32% NaOH). Subsequently, the pH is raised to 7.5 using an aqueous solution of sodium hydroxide (32% NaOH) and at this pH a solution of 252 g of sodium silicate (27% of Si? 2 in 252 g of deionized water is added. During this addition, the pH is kept constant using hydrochloric acid (15% HCl).

Subsequently, the pH is lowered to 2.0 using hydrochloric acid (15% HCl) and a solution of 3 g of SnCl x 5 H20 and 10 ml of 37% HCl hydrochloric acid is dosed in 90 ml of deionized water. During this addition the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). Subsequently, the pH is lowered to 1.8 using hydrochloric acid (15% HCl) and 476 ml of a TiCl 4 solution (400 g / 1) are dosed. During this addition the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). After the addition of the TiCl 4 solution, the mixture is stirred for 15 min and the prodrug is filtered, washed with deionized water, dried at 110 ° C and calcined at 850 ° C for 30 minutes. The interference pigment obtained has an intense red interference color.

Example 3 100 g of white mica (with a particle size of 10-60 μm) in 2 l of deionized water are heated at 80 ° C. Then, with vigorous stirring, a solution of 3 g of SnCl4 x 5 H20 and 10 ml of hydrochloric acid (37% HL) is added at a pH of 2.0 in 90 ml of deionized water. During this addition the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). Subsequently, at a pH of 1.8, 155 ml of a solution of TiCl 4 (400 g to TiCl 4 / l) are added. During this addition the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). Subsequently, the pH is raised to 2.6 using an aqueous solution of sodium hydroxide (32% NaOH). At this pH, 100 ml of a solution of 25 ml of a solution of TiCl4 (400 g of TiCl4 / l), 48 g of a solution of FeCl3 (14.25% of Fe) and 4.8 g of A1C13 x 6 H20 in water are added. deionized. During this addition, the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH).

Subsequently, the pH is raised to 7.5 using an aqueous solution of sodium hydroxide (32% NaOH) and at this pH 271 g of sodium silicate (27% of SiO 2) are added to 271 g of deionized water. The pH is kept constant using hydrochloric acid (10% HCl). Sub-succesively, the pH is lowered to 2.0 using hydrosulphuric acid (10% HCl), and a solution of 3 g of SnCl 4 x 5 H 0 and 10 ml of hydrochloric acid (37% HCl) is added to 90 ml of deionized water. . During this addition, the pH is kept constant using an aqueous solution of sodium hydroxide (50% NaOH). Subsequently, at a pH of 1.8, 45 ml of a solution of TiCl4 (400 g of TiCl4 / l) are added, again, the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). After this, the pH is raised to 2.6 using an aqueous solution of sodium hydroxide (32% NaOH) and at this pH 230 ml of a solution of 129 ml of a solution of TiCl4 (400 g of TiCl4 / l) are dosed. , 206 g of a solution of Fecl3 (14.25% Fe) and 10.2 g of A1C13 x 6 H20 in 157 ml of deionized water. During this addition, the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). Finally, the pigment is filtered by suction, washed with deionized water, dried at 11.0 ° C and calcined at 850 ° C for 30 minutes. The result is an interference pigment with an intense reddish violet color which turns orange to a strong yellowish green.

Example 4 The dehydrated pigment of Example 2 is calcined at 850 ° C for 30 minutes in a gas-forming atmosphere (N2 / H2; 85/15). The pigment prepared in this way exhibits an intense bronze effect and a strong luster.

Example 5 100 g of white mica (with a particle size of 10-60 μm) in 2 l of deionized water are heated at 80 ° C. Then, with vigorous stirring, a solution of 3 g of SnCl 4 x 5 H 2 O and 10 ml of hydrochloric acid (37% HCl) in 90 ml of deionized water is added at a dosing rate of 4 ml / min at a pH of 2.0. During this addition, the pH is kept constant using an asuous solution of sodium hydroxide (32% NaOH). Subsequently, at a pH of 1.8, 155 ml of a TÍCI4 solution (400 g of TÍCI4 / I) are added at a rate of 2 ml / min. During this addition, the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH) and at this pH 100 ml of a 25 ml solution of a TiCl 4 solution (400 g of TiCl / l) are added, 48 g of a FeCl3 solution (14.25% Fe) and 4.8 g of A1C13 x 6 H20. in deionized ..gi ^ a. During this addition, the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH).

Subsequently, the pH is raised to 7.5 using an aqueous solution of sodium hydroxide (32% NaOH) and at this pH it is dosed at a rate of 2 ml / min, 297 g of sodium silicate (27% of SiO2) in 297 g of deionized water. The pH is kept constant using hydrochloric acid (10% HCl). Subsequently, the pH is lowered to 2.0 using hydrochloric acid (10% HCl), and a solution of 3 g of SnCl4 x 5 H20 and 10 ml of slurhydrolyzed acid (37% HCl) is dosed at a rate of 4 ml / min. ) in 90 ml of de-sanitized water. During this addition, the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). Subsequently, at a pH of 1.7, 250.5 ml of a TiCl solution (400 g of TiCl 4 / l) is added at a rate of 2 ml / min, again, the pH is kept constant using a Subsequently, the pigment is filtered by suction, it is washed with deionized water and dried at 110 ° C. After this stage the pigment obtained has a reddish violet color that turns yellowish green.

Finally, the pigment is calcined at 850 ° C for 30 minutes. The result is an interferential pigment with a yellowish-red luster, its color being yellowish green.

Example 6 The metal oxide layers are precipitated as in Example 5. In addition, at a pH of 2.6, 130 ml of a mixture of 129 ml of a solution of TiCl 4 (400 ml) are added at a rate of 1 ml / min. g of TiCl4 / l), 147 ml of a solution of FeCl3 (14.08% Fe), 10.2 g of A1C13 x 6 H 0 and 157 ml of deionized water. During this addition, the pH is kept constant using an aqueous solution of sodium hydroxide (32% NaOH). The pigment is worked up as in Examples 1-5.

The dry pigment exhibits an intense reddish violet color of high luster that turns orange. After calcining, the pigment has a yellowish red luster, with the color turning to a strongly lustrous yellow.

Example 7 The dry product of Example 4 is calcined at 850 ° C for 30 minutes in a gas-forming atmosphere (N2 / H2, * 85/15). The pigment prepared in this way exhibits a bronze-red effect and a strong luster and also a high opacity. When it turns, the color changes to a strong yellowish green.

Example 8 The solid product of Example 5 is calcined at 850 ° C for 30 minutes in a gas-forming atmosphere (N2 / H2; 85 / * 5). The pigment prepared in this way exhibits a deep bronze-red effect and a strong luster and also a high opacity. When it turns, the solom sambia to a strong golden yellow.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (1)

1. Interference pigments based on platelet-shaped substrates, with multilayer coatings, with at least one sequence of layers, characterized in that it comprises: (A) a coating having a refractive index of n j > 2.0, (B) a colorless reuphoria having a refractive index of n < .l. 8, and (C) a non-absorbent coating of a high refractive index and, if desired, (D) a protective outer layer. . Interference pigments in accordance with Claim 1, characterized in that between the substrate (S) and the sap (A), the layer (A) and (B), the layer (B) and (C) and / or the layer ( C) and (D) there is also another layer of colorless or colorless metal oxide (SI), (Al), (Bl) and / or (Cl). Interference pigments according to Claim 1 or 2, characterized in that the platelet-shaped substrates are thin of natural or synthetic mica, glass, Al 2 O 5, Si 2 or Ti 0 and platelet-shaped materials coated with metal oxides. The interference pigments according to one of Claims 1 to 3, characterized in that the layers (A), (B) and (C) consist essentially of metal oxides. The interference pigments in accordance with one of claims 1 to 4, characterized in that the sap (A) consists essentially of titanium dioxide, iron oxide, bismuth oxychloride, zirconium oxide, tin oxide, zinc oxide, titanium suboxides, iron titanates, iron oxide hydrazes, chromium oxide, bismuth vanadate, cobalt aluminate or mixtures thereof. The interference pigments according to one of Claims 1 to 5, characterized in that layer (B) consists essentially of silicon dioxide, aluminum oxide, magnesium fluoride or mixtures thereof. The interference pigments according to one of Claims 1 to 6, characterized in that the layer (C) consists essentially of titanium dioxide, bismuth oxychloride, zirconium oxide, tin oxide, zinc oxide or mixtures thereof. The interference pigments in soundness are one of Claims 1 to 7, characterized in that they have up to four times the sequence of layers (A) - (C). The interference pigments according to claim 8, characterized in that they contain only one layer of the sequence (A) - (C). The process for preparing the interference pigments according to one of Claims 1 to 8, characterized in that the metal oxides are applied only to water in platelet-shaped substrates by the hydrolytic decomposition of the metal salts in an aqueous medium. . The use of the interference pigments according to Claim 1 in paints, lacquers, printing inks, plastics, ceramic materials, glasses and cosmetic formulas. Interference Pigments SUMMARY »The present invention relies on interferensi pigments based on platelet-shaped substrates coated with several plates and comprises at least one layer of the sequence comprising: (A) a coating having a refractive index of n > . 2.0, (B) a colorless coating having a refractive index of n < 1.8, and (C) a non-absorbent coating of high refractive index and, if desired, (D) an outer protective layer.